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Vibrationally Enhanced Quantum Transport


The transport of quantum excitations along coupled quantum systems has received considerable attention in the literature recently, the motivation for which has been to explain the possible need for quantum mechanics in photosynthesis. For this reason researchers have been striving to answer the question of whether the presence of quantum coherence or quantum noise assists in the directed transfer of excitations in coupled systems. Recently it was shown that the transport of an excitation along a linear chain of coupled two level systems may be enhanced with a collective coupling to a driven vibrational mode. In this presentation, we first incorporate the results from quantum ratchet theory to extend this vibrationally assisted transport scheme, investigating the case of coupling to a collective vibrational mode without driving, a type of quantum Rube Goldberg machine. We find that directed transport only occurs at specific mechanical frequencies and determine the relationship between this frequency and the system parameters. Second, we investigate the presence of multiple collective driven vibrational modes to facilitate directed transport, showing that transport of excitations can occur over a broad range of mechanical driving strengths.